[Pacemaker] iscsi target mounting readonly on client

[Joseph-Andre Guaragna]

Hi Felix,

Sorry for the late answer. I gave a try to your suggestions, it worked
immediately with block io and the increase block timeout.

I stick with iet for now as my supervisor want to stick to standard pacakges.

You really save my day.



Best reagards,



   Joseph-André GUARAGNA



2013/4/14 Joseph-Andre Guaragna <joseph-andre at rdmo.com>
>
> Thanks for the informations. I give it a try monday and gave you a feedback.
>
>
>
> 2013/4/12 Felix Zachlod <fz.lists at sis-gmbh.info>:
> > Hello Joseph!
> >
> >> -----Ursprüngliche Nachricht-----,
> >> Von: Joseph-Andre Guaragna [mailto:joseph-andre at rdmo.com]
> >> Gesendet: Freitag, 12. April 2013 17:19
> >> An: pacemaker at oss.clusterlabs.org
> >> Betreff: [Pacemaker] iscsi target mounting readonly on client
> >
> > You have to make two things absolutely shure.
> >
> > 1. Data that has been acknowledged by you iscsi Target to your initiator has
> > hit the device and not only the page cache!
> >
> > If you run your target in fileio mode you have to use write trough- cause
> > with write back you or your cluster manager can't ever tell if the writes
> > have completed before switching the DRBD states.
> > That will only perform good if you have a decent raid card with BBWC! BUT
> > YOU MUST RUN WRITE TRHOUGH or blockio (which will be write trough too)
> > running write back in such a constellation IS NOT SAFE you might risk
> > SERIOUS DATA CORRUPTION when switching targets.
> >
> > 2. On your initiator side try to rise the /sys/block/sd*/device/timeout
> > value. That is the time the block device will wait for a command to complete
> > before handing an i/o error tot he upper layer- which will most probably
> > lead to your filesystem remounting r/o.
> >
> > 3. This is just a side note: do not use iet. We were running a production
> > target wit iet for about 2 year which caused horrible problems to us.
> > Consider scst or lio (I personally do not have any experiences with lio but
> > scst is running in our production environment for years now without any
> > problems)
> >
> > regards
> > Felix
> >
> >
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